(1) Field of the Invention
The present invention relates to substrate treating apparatus for resist-coating, developing, cleaning or otherwise treating substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, substrates for optical disks and the like, by supplying thereto a treating liquid such as a photoresist solution, developer or deionized water. More particularly, the invention relates to a technique of accommodating holder arms supporting treating devices such as treating solution supply nozzles or brushes.
(2) Description of the Related Art
Conventional substrate treating apparatus will be described hereunder, taking, for example, apparatus for supplying a resist to substrates such as semiconductor wafers to coat the wafers with the resist.
Conventional resist coating apparatus may be classified broadly into two types as shown in FIGS. 1 and 2.
(1) A resist coating apparatus of the first type will be described with reference to FIG. 1. Numeral 1 denotes a spin chuck for rotatably supporting a wafer W to be treated. The wafer W is surrounded by a scatter preventive cup 2 for preventing scattering of the resist. In a standby position laterally of the scatter preventive cup 2 are a plurality of, e.g. five, holder arms A-E of different lengths having treating solution supply nozzles Na-Ne attached to distal ends thereof for supplying the resist to the wafer W. These five holder arms A-E are arranged parallel to one another and in descending order of length toward the scatter preventive cup 2. The respective holder arms A-E are swingable in a horizontal plane about proximal ends Pa-Pe.
A given one of these five holder arms A-E, e.g. the holder arm B, operates as follows. The holder arm B is first raised from the standby position to a height for movement. The holder arm B raised is swung in the horizontal plane, whereby the treating solution supply nozzle Nb attached to the distal end thereof is moved to a position over the spin center of wafer W. Next, the holder arm B is lowered to lower the treating solution supply nozzle Nb to a resist discharge position. The resist is supplied in a predetermined quantity to the wafer W from the treating solution supply nozzle Nb in the discharge position. When the resist has been supplied, the wafer W is spun at high speed to form a uniform resist layer on its surface. Subsequently, the holder arm B is raised to the height for movement, swung back toward the standby position, and lowered to the standby position which completes the series of processes.
The holder arms A, C, D and E are operable in the same way as the holder arm B.
(2) A resist coating apparatus of the second type will be described with reference to FIG. 2. In a standby position laterally of a scatter preventive cup 2 are a plurality of, e.g. five, holder arms A-E of the same length having treating solution supply nozzles Na-Ne attached to distal ends thereof. These five holder arms A-E are arranged parallel to one another with the distal ends pointing toward the spin chuck 1. The holder arms A-E are mounted on a uniaxial drive mechanism 91. The uniaxial drive mechanism 91 is slidable in directions perpendicular to a longitudinal direction of holder arms A-E. Each holder arm A-E is slidable longitudinally thereof.
A given one of these five holder arms A-E, e.g. the holder arm E, operates as follows. First, the uniaxial drive mechanism 91 slides to move the holder arm E into alignment with the spin center of spin chuck 1. Then, the holder arm E is driven to slide longitudinally thereof from the standby position to move the treating solution supply nozzle Nb to a discharge position over the spin center of wafer W. The resist is supplied in a predetermined quantity to the wafer W from the treating solution supply nozzle Nb in the discharge position. When the resist has been supplied, the wafer W is spun at high speed to form a uniform resist layer on its surface. Subsequently, the holder arm E is driven to slide back to the standby position, to complete the series of processes. The holder arms A-D are operable in the same way as the holder arm E.
The foregoing conventional apparatus have disadvantages as set out hereunder.
Each of the two conventional apparatus provides a standby space laterally of a substrate treating region enclosed by the scatter preventive cup 2. In the standby space, the holder arms are arranged in horizontal posture and extend in the same direction. This arrangement results in a large area within the substrate treating apparatus occupied by the standby space. Especially, with the recent trend toward increased sizes of semiconductor wafers, the holder arms inevitably have extended lengths which require an enlarged standby space. In addition, to achieve improved efficiency of treatment and to enable use of plural types of treating solutions, a single apparatus is required to include multiple treating devices available for selective use. The number of holder arms for individually supporting these treating devices tends to increase, which also is a factor to enlarge the standby space.